What Causes Erectile Dysfunction?

Physical, psychological and medication-related causes explained.

Part of the Access Doctor Erectile Dysfunction guide.

Physical Causes of Erectile Dysfunction

At its most fundamental level, ED is caused by disrupted blood flow to or within the penis. The following conditions can interfere with this:

• Cardiovascular disease — atherosclerosis reduces blood flow throughout the body, including to the penis; ED is often an early marker of arterial disease
• Diabetes — causes both nerve damage (diabetic neuropathy) and blood vessel damage; affects erectile function through both pathways
• High blood pressure (hypertension) — damages blood vessel walls over time and reduces penile blood flow
• High cholesterol — contributes to arterial narrowing
• Low testosterone (hypogonadism) — reduces libido and may impair erectile response; thyroid disorders also contribute
• Neurological conditions — Parkinson’s disease, multiple sclerosis, spinal cord injury, epilepsy
• Peyronie’s disease — scar tissue inside the penis causing curved, painful erections
• Obesity — increases cardiovascular risk, disrupts hormone balance, impairs blood vessel function
• Sleep apnoea — reduces oxygen delivery and is associated with lower testosterone levels
• Pelvic surgery — particularly radical prostatectomy; see our guide to surgery and erectile dysfunction

Psychological Causes of Erectile Dysfunction

Psychological factors are particularly common in younger men experiencing ED, but can affect men of any age. They include:

• Performance anxiety — fear of not being able to achieve or maintain an erection creates a self-fulfilling cycle; the most common psychological cause
• Depression — reduces libido and affects the neurological pathways needed for sexual arousal
• Stress and fatigue — chronic stress suppresses testosterone and interferes with sexual function
• Relationship problems — communication issues, conflict, or reduced emotional intimacy
• Sexual trauma or past negative experiences

Medications That Can Cause Erectile Dysfunction

Several commonly prescribed medications list ED as a known side effect. Do not stop any medication without discussing alternatives with your prescriber first.

When to See a Doctor About ED

• ED has persisted for more than 2–4 weeks
• It is causing distress or affecting relationships or quality of life
• You have cardiovascular risk factors (diabetes, high blood pressure, high cholesterol)
• ED began after starting a new medication
• You are under 40 with unexplained ED — a thorough assessment is particularly important